According to prosecutors, Callahan showed police a mobile-phone video of S.E. beating her child. S.E. told police that she had been told to do so by Callahan and Hunt and that Callahan threatened to show police the video if she "messed up" or went to authorities.
S.E. was released from jail in February after being sentenced to time served on the abuse charge, and her daughter is now in foster care, said Michael Tobin, a spokesman for the U.S. attorney's office.
Once the full picture emerged, Ashland police called in the FBI, "and shortly after, the suspects were indicted," Marcelli said.
'All of us...need to work on being better neighbors'
Callahan and Hunt kept tabs on the woman and child with a baby monitor, with Hunt taking the woman's government benefit cards, authorities said.
"Callahan and Hunt forced S.E. to clean the house, do laundry, walk to the store to do their shopping and care for their numerous pit bulls and reptiles," the prosecution statement said. Her child was kept in the apartment when she was sent to the store, they said.
Tuesday's announcement comes more than a month after the rescue of three women from a Cleveland home where police said a man had held them captive for about a decade.
Authorities believe there is no connection between the Ashland investigation and that case, the law enforcement source said.
Dettelbach, the federal prosecutor, said Tuesday's arrests are part of a broader push to crack down on what he called "modern-day slavery."
"We need your help in these efforts. Law enforcement cannot do it alone. All of us in the northern district of Ohio need to work on being better neighbors," he said. "We need to ask questions, hard questions, when we see something that doesn't look right. We need to not be afraid to pick up the phone and to call law enforcement. We need to not be afraid to ask those simple questions -- is everything OK? Is there some way I can help you? As Ohioans and as Americans, that is who we are, and it is our duty. "